Differential interplay between protein kinase C and Rho-kinase in the endothelin-1-induced and pressure-induced contractions of rat posterior cerebral artery.

To clarify the involvement of protein kinase C and Rho-kinase in the contractile activation of cerebral artery in response to endothelin-1 and pressurization, rat posterior cerebral artery (outer diameter, 100-200 microm) was mounted in arteriograph, and the changes in cytosolic Ca2+ and vessel diameter were measured by video-microscopy in connection with an Argus 50 system. Endothelin-1 (10 nM) induced a tonic contraction with a slight increase in cytosolic Ca2+, which was mostly dependent on protein kinase C (chelerythrine sensitive). Intraluminal pressurization (60 mmHg) also produced contraction with a low cytosolic Ca2+, which was myogenic in nature and dependent on both protein kinase C and Rho-kinase (Y-27632 sensitive). The results suggest differential interplay between protein kinase C and Rho-kinase in the endothelin-1-induced and pressure-induced tonic phase of contractions in the rat posterior cerebral artery.